Fe-based Amorphous Alloy Crystallization Kinetics

Fe-based amorphous alloys have very excellent soft magnetic properties.This paper designs and optimizes through the composition on the basis of FINEMET alloys, substitute the noble metal Nb element with Ni partly. The alloy ingots were prepared by arc melting under the titanium-gettered argon atomsphere. A single-roller melt spinning method is employed to prepare Fe73.5Cu1Nb3-xSi13.5B9Nix(x=0, 0.5, 0.8, 1.0, 1.5)amorphous ribbons. The microstructures and the amorphous properties of the as-spinning alloys are characterized X-ray diffraction and differential Scanning Calorimetry.Using differential scanning calorimetry (DSC) on iron-based amorphous alloy and other mild non-isothermal crystallization kinetics were studied, found that as the amount of Ni with increasing crystallization temperature, TX, and began to crystallization peak temperature Tp are In the lower, that amorphous alloy crystal nucleation activation energy and activation energy of growth is reduced, the crystallization behavior easier. At the same time amorphous alloy A-0, A-2, A-3, A-4 Isothermal DSC curve showed a single exothermic peak, with the Ni content increases dramatically narrow exothermic peak width, the birth of various amorphous alloys time is very short, once again shows that the crystallization behavior significantly easier. Arrhenius equation with isothermal calculate the A-0, A-2, A-3, A-4 of the crystallization activation energy were 425.4KJ/mol, 387.5KJ/mol, 398.6KJ/mol, 397.1KJ/mol, Ni alternative Nb element crystallization activation energy decreased in varying degrees, that partial replacement of Ni element after some weakening FINEMET Nb element thermal stability. Isothermal crystallization volume fraction and the time for "S" curve, isothermal JMA curve is linear.JMA model using amorphous alloy A-0, A-2, A-3, A-4 of the isothermal crystallization process was analyzed and found that precipitation of a single Fe3Si phase, temperature, incubation period decreases, the reaction peak width decreases, the crystallization behavior easier. At the same time amorphous alloy A-0, A-2, A-3, and A-4 at different temperatures Avrami index remained at about 1.5, at different temperatures did not change the crystallization mechanism, indicating that amorphous alloy is a non- crystal matrix, the small size of stored grain growth started, especially in the area of short range order existing nuclei grow directly completion of precipitation Fe3Si phase, followed by the nucleation rate is almost zero.